1. Field of the Invention
The present invention relates to an interruption and disconnecting device for high- and/or medium-voltage applications, which contains dielectric insulation means and has a particular structure, so as to allow the reduction of the environmental impact of said insulation means.
2. Description of the Related Art
It is known that the interruption and disconnecting devices of the art generally comprise at least one interruption chamber and a disconnection chamber which are connected to insulating bushings. These elements are arranged inside a structure which is sealed with respect to the surrounding environment and is filled with a fluid insulating medium. With reference to FIG. 1, a block diagram is presented which illustrates an example of a typical structure of a known interruption and disconnecting device used in a high-voltage substation.
A conductor of a main power line, indicated by the arrow 2, is connected to a main distribution bar 3 by means of the interruption and disconnecting device 1. Said interruption and disconnecting device 1 comprises an insulating bushing 4 for connection to the line 2. a disconnection chamber 5, an interruption chamber 6, electric current measuring devices 7 and 8 arranged at the ends of the interruption chamber 6, and an insulating bushing 9 for connection to the bar 3 by means of a conductor 10. There are also two devices 11 and 12 used to earth the system.
The disconnection chamber 5 can be arranged both upstream and downstream of the interruption chamber 6.
The device 1 is completely filled with an insulating medium in order to prevent electrical discharges between the various parts that are at high potential differences.
A known embodiment of an interruption and disconnecting device according to the block diagram of FIG. 1 is presented with reference to FIG. 2. The insulating bushings 4 and 9 are arranged respectively in input and in output with respect to the interruption and disconnecting device 1. The insulating bushing 4 contains the conductor 2 of the main power line, while the insulating bushing 9 contains the conductor 10 connected to the main distribution bar (not shown in FIG. 2).
The insulating bushing 4 is connected to the disconnection chamber 5 by means of a coupling 13. The disconnection chamber 5 contains a fixed contact 14 and a moving contact 15 for performing disconnection. An earthing device 11 is also connected to the chamber 5 and connects, if required, the main conductor 2 to the outer casing, 16 of the device 1, which is at ground potential by means of the supports 17, 18 and 19. Actuation elements 20 for moving the moving contact 15 are also placed inside the disconnection chamber 5. The disconnection chamber 5 is furthermore separated from the insulating bushing 4 and from the disconnection chamber 6 by means of the insulating partitions 21 and 22.
The interruption chamber 6 contains a moving contact 23 and a fixed contact 24. The moving contact 23 is actuated by movement elements 25. Further, the earthing device 12 is connected to the interruption chamber 6 and places the conductor 26 in output from the disconnection chamber at ground potential. The moving contact 23 is connected to the conductor 10 in output from the interruption and disconnecting device 1. The interruption chamber 6 is separated from the insulating bushing 9 by means of the insulating partition 28. The insulating bushings 4 and 9, the interruption chamber 6 and the disconnection chamber 5 are completely filled with an insulating fluid, generally sulfur hexafluoride (SF6), having a pressure which is higher than the atmospheric one. In order to maintain said internal pressure, required in order to achieve reduced insulation distances and therefore reduce the dimensions of the structure. the device 1 is completely sealed with respect to the outside environment.
Alternative configurations with respect to the one described in FIGS. 1 and 2 are possible. In particular, it is possible to use multiple disconnection chambers and multiple insulating bushings if it is necessary to connect multiple distribution bars to the main power line.
In the interruption and disconnecting devices of the art, the insulation fluid that is generally used is sulfur hexafluoride (SF6). Other known fluids are fluorocarbons (FC), perfluorocarbons (PFC), perfluoropolyethers (PFPE) or mixtures thereof.
The use of these insulation means, particularly SF6, which has the highest dielectric insulation capacity, allows to considerably reduce the insulation distances and therefore to considerably reduce the dimensions of each single device, and therefore of the substation in which it is used, with respect to the use of insulating means, such as mineral oils. This fact leads to a considerable reduction in installation and operating costs.
It is known from the technical literature that known fluoridized gaseous insulating means, in particular SF6, may cause problems in terms of environmental impact; furthermore they are considerably expensive.
Reducing the content of these insulating means by using alternative dielectric fluids, such as for example mixtures of SF6 and nitrogen (N2), pure nitrogen or noble gases leads to an increase in the required insulation distances, since said alternative fluids have, for an equal pressure, a much lower dielectric strength and arch quenching power than, for example, SF6 used in its pure state. Simple replacement of SF6 with other alternative insulation fluids without performing any structural modification to the interruption and disconnecting device would cause malfunctions.
On the other hand, if the pressure of said alternative insulating fluids is increased so as to ensure satisfactory dielectric strength and arc quenching power, it is necessary to resort to complicated structures which are economically scarcely competitive and scarcely reliable.
The aim of the present invention is to provide an interruption and disconnecting device for high- and/or medium-voltage applications, whose structure has a reduced complexity and is capable of optimizing the use of the insulation means used, so as to considerably reduce their environmental impact.
Within the scope of this aim, an object of the present invention is to provide an interruption and disconnecting device for high- and/or medium-voltage applications. which has a modular structure which allows to partition the volume of the insulating fluids used inside the interruption pole.
Another object of the present invention is to provide an interruption and disconnecting device for high- and/or medium-voltage applications, in which it is possible to use different insulation means inside the interruption pole.
Another object of the present invention is to provide an interruption and disconnecting device for high- and/or medium-voltage applications, which allows easy maintenance and/or replacement of the electric actuation elements, particularly of the parts that are most exposed to wear, such as the fixed contact and the moving contact of the interruption chamber.
Another. but not last, object of the present invention is to provide an interruption and disconnecting device for high- and/or medium-voltage applications. which is highly reliable and relatively easy to manufacture and at competitive costs.
This aim. these and other objects, which will become more apparent hereinafter, are achieved by an interruption and disconnecting device for high- and/or medium-voltage applications, comprising a disconnection chamber and an interruption pole having a free volume accommodating an interruption chamber which contains a moving contact and a fixed contact, said interruption pole and said disconnection chamber containing dielectrically insulating fluids. The device according to the invention is characterized in that said interruption chamber is sealed.
In this way. the device according to the invention has a modular structure which allows to optimize the use of dielectric fluids and to reduce the environmental impact; in fact, the dielectric fluids which have a high environmental impact are used only in the sealed interruption chamber where a high arc quenching power is required.
Another advantage of the device according to the invention, consists in the fact that the interruption chamber can be extracted from the main body of the electric interruption pole. This allows easy maintenance and/or replacement of the parts most subject to wear during the interruption and disconnection actuations by virtue of the possibility to extract the sealed interruption chamber from the body of the electric pole. Furthermore, the device according to the invention is constituted by a relatively small number of parts and ensures high reliability and easy execution.